Fabrication of anti-reflective microstructures on chalcogenide crystals by femtosecond laser ablation

A Yb femtosecond laser was used to fabricate antireflective microstructures on CdSSe single crystal samples. We investigated several microstructure fabrication methods, including direct single pulse ablation using 200 fs pulses, ablation with in-depth focusing, ablation in the presence of additional spherical aberration and ablation with obstruction of peripheral rays. We performed a comprehensive analysis of the implemented antireflection microstructure fabrication methods. The performances of the antireflection microstructures were measured using an infrared Fourier spectrum analyzer and the best samples demonstrated $>99\%$ transmission in the 4.5–6 µm range and average transmission near $97\%$ in range from 2.7 to 8 µm.